For a bash script I want to determine whether my device has Wi-Fi. The easiest way for me would be ifconfig and some regex. So I want to check if my interface en0 has a valid IP or not.
ifconfig en0 | grep inet | cut -d: -f2 | awk '{ print $2}'
gives me the IP. If I dont have one it doesn't return anyhting since the grep command returns nothing. How do I check for that in an if for example?
I managed to put this together with info I found on other sites.
#!/bin/sh
IP_ADDRESS=$(ifconfig en0 | grep inet | cut -d: -f2 | awk '{ print $2}')
IP_ADDR_VAL=$(echo "$IP_ADDRESS" | grep -Ec '^(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9])\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[0-9])')
if [ $IP_ADDR_VAL -eq 0 ]; then
echo not valid
else
echo valid
fi
Actually I noticed the inet part being only there when I'm connected, so a piped grep inet should do the job just fine!
my ifconfig output is different
inet addr:192.168.210.140 Bcast:192.168.215.255 Mask:255.255.248.0
inet6 addr: fe80::92fb:a6ff:fe66:970/64 Scope:Link
however the difference is not great u will find out what u need to change (I understand u need to check one interface - here eth0; every interface has one inet line)
if [[ `/sbin/ifconfig eth0 | grep -e 'inet ' | cut -d ' ' -f12 | grep -E "^addr:[0-9]{3}.[0-9]{3}.[0-9]{3}.[0-9]{3}$" | wc -l` -eq 1 ]]; then
echo "correct IP";
else
echo "no IP";
fi
echo " assigned";
